In accordance with a rapid spread of information relevant apparatuses and communication apparatuses such as a personal computer, a video camera and a portable telephone in recent years, the development of a battery to be used as a power source thereof has been emphasized. The development of a high-output and high-capacity battery for an electric automobile or a hybrid automobile has been advanced also in the automobile industry. A lithium battery has been presently noticed from the viewpoint of a high energy density among various kinds of batteries.
Liquid electrolyte containing a flammable organic solvent is used for a presently commercialized lithium battery, so that the installation of a safety device for restraining temperature rise during a short circuit and the structure for preventing the short circuit are necessary therefor. In contrast, an all solid lithium battery all-solidified by replacing the liquid electrolyte with a solid electrolyte layer is conceived to intend the simplification of the safety device and be excellent in production cost and productivity for the reason that the flammable organic solvent is not used in the battery. Moreover, an all solid state battery utilizing a sulfide solid electrolyte material has an advantage of being excellent in Li ion conductivity.
For example, Patent Literature 1 discloses a coated cathode active material comprising a cathode active material (such as LiNi1/3Co1/3Mn1/3O2) and a coating layer (such as LiNbO3), wherein a carbonate concentration in the coating layer is in the range of 800 ppm to 3500 ppm. Patent Literature 1 discloses an all solid state battery comprising a cathode layer containing a coated cathode active material, an anode layer containing graphite as an anode active material, and a solid electrolyte layer containing a sulfide solid electrolyte material. The object of Patent Literature 1 is to decrease of a battery resistance.